Process for improving the color stability of hydrocarbons with hydrazines



March 14, 1961 Q THOMAS ET AL 2,975,136

PROCESS FOR IMPROVING THE COLOR STABILITY OF HYDROCARBONS WITHHYDRAZINES Filed Jan. 17, 1956 Disfillofes Treated Vapors 24 20-Hydroxyelhyl Vapor Hydrozine Crude Treatment Pelroleum l NGOH Residuel9 l4 l l Hydmzine Distillation l8 N OOH i Treatment Hydrdzine ResidueINVENTORS CHARLES L.THOMAS ARCHIBALD F! STUART HABET M. KHELGHATIANATTORN Y PROCESS FOR IMPROVING THE COLOR STA- BILITY F HYDROCARBONSvWITH HYDRA- Charles L. Thomas, Swarthmore, Archibald P. Stuart, Media,and Habet M. Khelghatian, Springfield,'Pa.,' assignors to Sun OilCompany, Philadelphia, Pa a corporation of New Jersey v Filed Jan. 17,1956, Ser. No. 559,725

Claims. (Cl. 252-515)- This invention relates to producing hydrocarbonshaving improved properties including color stability.

The color stability of hydrocarbons such as petroleum products is animportant property with respect tomany uses thereof, and many productsas ordinarily-produced have color stability which is unsatisfactory,because of the presence of various constituents, believed to be mainlynonhydrocarbon materials, which cause thehydrocar bons to discolor whensubjected to conditions of storage and use. V

Accordingto one embodiment of the present invention; petroleumproductsare rendered more color stable by reacting certain constituentsthereof with hydrazine or specified derivatives thereof. The hydrazinetreating agent may react with oxygen'dissolved in the oil or withconstituents of the oil which would otherwise produce color degradation.In any event, the result obtained avoids the formationof the ultimateproducts which ormally cause poor color characteristics in petroleumprod: ucts.

The invention will be further described vith regard to treatment ofpetroleum products. However, it is to be understood that otherhydrocarbon-containing materials such as shale oil can also'be treatedaccording to the invention. v

The hydrazine treating agent which is employed comprisesa'compound'having the following formula:

where R and R are each selected from the group consisting of hydrogen,hydrocarbon radicals, acyl radicals, carbamyl radicals, andthiocarbamylradicals, and R and R are each selected from the group consisting ofhydrogen, alkyl radicals, hydroxyallryl radicals and halophenylradicals. Examples of suitable hydrazine treating agents are; hydrazine,methyl hydrazine, symmetrical dimethyl hydrazine, asymmetrical dimethylhydrazine, asymmetrical. methyl-ethyl hydrazine, asymmetrical diethylhydra-. zine, trimethyl hydrazine, octyl hydrazine, phenyl hydrazine,asymmetrical [diphenyl hydrazine, asymmetrical methyl phenyl hydrazine,N- cyclohexyl hydrazine, acetyl hydrazine," semicarbazide, Vthiosemicarbazide, N-ethoxy hydrazine,N-v(chlorophenyl) hydrazine, etc.Preferably, the hydrazine treating agent according to the'inventioncontains not more than, 50 carbon atoms in the molecule, and morepreferably not more than carbon atoms.

rP referablyR and R if hydrocarbonradicals, are saturated hydrocarbonradicals, rather'than aromatic'or olefinic radicals. Preferably, atleast oneof the radicals, R R R or R is hydrogen. 7 f v The contactingof petroleum products with a-hydrazine treating agent can be carried outat any, suitable tempera.- ture withinthe approximate rangefromatmospherictem perature tOG-SO F. Preferably thetcmperature isWithin the approximate range from 150 F. to 450 F. Atthe highercontacting temperatures, the hydrazine treating r a Patented Mar.: 14,-3

agent employed preferably one which has relatively high molecularWeight, in order that the treating: agent does not have excessivevolatility at the temperatureem- I ployed." .It is not essential howeverthat the hydrazine} treating agent be in liquid phase at thecontacting-1mm? I f perature, since the inventioncontemplatesjthecontacting of petroleum products with a hydrazinetreating agent in vapor phase, in cases where the hydrazinetreatingagent employed is capable of existing in the vapor state.

The amount of hydrazine or derivative thereof (anhydrous basis) ispreferably within the approximate range from 0.005 to 0.5 weight percentbased on the petroleum treated. However, larger amounts may be neededwhere the petroleum contains particularly large amounts ofconstituents-which it is desired to react with the hydrazine treating."agent. The time required-for reaction between hydrazine treating agent:and constituents of the petroleum treated depends on the temperature andother conditions employed.

Atthepreferred elevated temperatures, reaction may take place in aminuteoreveri less, and it will usually be unnecessary to prolong thereaction beyond one hour. When lower temperatures are used, longerreaction times, e.g. 10 hours or more, maybe needed. Any water formed inthe reaction, and perhaps theexcess treating agent also; can be removeddirectly upon completion of thereaction, or at any convenient latertime. I:

When, assubsequently more fully described, hydrazine or a derivativethereof is used as a stabilizing additive for petroleum, the period oftime involved may becon siderablylonger. Thus, it may be desired to'havethe additive in. the petroleum material during an entire storageortransportation period, with removal of 'a'ny. water formed and.perhaps the excess additive also, onlyv at the end of the storageortransportation period. t In cases where the hydrazine treating agentreacts with nonhydrocarbon constituents of the petroleum material,

water 'isoften produced as a product of the reaction. I It is generallydesirable, when. this is thecase, to remove the water formed from thepetroleum product by anynof the conventional methods for removal ofwaterfrom petroleum fractions, e.g; by blowing with air, etc.- ,,When 1 suchmeans'are used to remove water from the, treated petroleum product,excess hydrazine treating agentgif any, may 'also'be at least partiallyremoved. Thisisparticularly true in the case of hydrazine itself, whichhas aboiling point'not greatly different from that of wat'er.

The'present invention can be carried out,'in one em a two-phase systemincluding a treated petroleumphase and ahydrazine treating agent phase.Thelatter vphase may contain at least some of the; reaction productspro! duced in the treating, and may also contain some ofthe' 7 i morehighly polar hydrocarbonconstituentswhich were, we extracted bythe-hydrazine treating agent. In such op; eration, the amount ofhydrazine treatingagent employed may greatly exceed the amount ofpetroleum treated, the exact amount to be used depending on the amountof petroleum constituents desired to be extracted. If dc sired, amodifying solvent such as water can be employed; 1 to reducev themiscibility of the hydrazine treating agent j with the petroleumfraction. I a

In one embodiment of theprocess according, to theqinvention thecontactingof petroleum with hydrazinetreah somecases, the hydrazinetreating agent increa'se ability of thealk'alii'metalhydroxideetoreact-zwithflun-' f u desirable constituents of the petroleum fractiominorder that such constituents can beremovedtherefrom. 21f

desired, the petroleum fraction thus treated can be distilled in thepresence of the alkali metal hydroxide and hydrazine treating agent. Ithas been found that distillates can be obtained in this manner whichhave better color stability than those obtained by distillation in thepresence 'of alkalin'retal. .hydroxidefwithout a hydrazine treatingagent. i t I In one embodiment offthe inventi n, hydrazine or aderivative thereof as previously defined can be employed as anadditivefor petroleum products, to improve. the color stability and' oxidationresistance of the. products, Thus, for example, .0.005'to 0.5 weightpercent of hydrazine or derivative'tanhydrous basis). can be employed asa lubricating oil additive. Inv gasoline, tlielamounts used areconveniently in the approximate range from p.p.m. to 0.05weightpercentJIt' has been found 'for example that 10 p.p.m. of'hydrazine is aneffective stabilizer for catalytically cracked gasoline. It is notessential, in this embodiment of the invention, that water formed byreaction of hydrazine or derivative thereof with constituents of thepetroleum, be removed from the petroleum. However, such removal will bepreferable in many instances where the presence of water in the productwould produce an undesirable haze.

The invention will be further described with reference to the attacheddrawing, which is a schematic flow sheet of one embodiment of theprocess according to the invention.

Referring to the drawing, crude petroleum is introduced into toppingzone 10 through line 11, and a conventional topping operation isperformed to obtain distillates removed as indicated by'line 12. Theresidue, or reduced crude, is introduced through line 13 into hydrazinetreating zone 14, wherein it is contacted with hydrazine, e.g. anaqueous solution thereof, introduced through line 15. If desired, thetreatment can be carried out in the presence of sodium hydroxideintroduced, for example as aqueous caustic soda, through line 16. Thevarious materials can be agitated together by suitable conventionalmeans in zone 14, for a period of about one hour, for example, at atemperature of about 150 F. The entire mixture is then introducedthrough line 17 into distillation zone 18. Evolved lubricating oilvapors are withdrawn through line 19 and introduced into vapor treatmentzone 20; Residue from the distillation is withdrawn through line 21.

Beta-hydroxyethyl hydrazine is introduced into zone 20 through line 24,and aqueous caustic soda is introduced through line 22. Alternatively,if desired, the hydroxyethyl hydrazine and aqueous sodium hydroxide canbe mixed and introduced together into zone 20. The Inbricating oilvapors are refined by contact with the sodium hydroxide andhydroxyethylhydrazine, acidic constituents of the vapors being neutralized by thesodium hydroxide, and reaction occurring between the hydroxyethylhydrazine and nonhydrocarbon constituents of the vapors. Thehydroxyethyl hydrazine is vaporized to a substantial extent under thetemperature conditions in the zone 20, and the hydroxyethyl hydrazinevapors are removed along with the treated vapors through line 23. Thevapors withdrawn through line 23 can then be'subjected to rectificationby conventional means not shown to produce various distillate fractions.The hydroxyethyl hydrazine withdrawn through line 23 will becomeincorporated in some of these distillate fractions, depending on theirboiling ranges. All of the distillates obtained are beneficiallyaffected by the contact with hydroxyethyl hydrazine and sodium hydroxidein zone 20, and those distillates which contain hydroxyethyl hydrazineafter condensation are beneficially stabilized against degradation bythe presence of hydroxyethyl hydrazine. If desired, some or all of thedistillates obtained can be further contacted with a hydrazine treatingagent either at the temperatures at which they are withdrawn from thedistillation column, or at other suitable temperature. T

U Although the treatment with hydrazine in zone 14 and the treatmentwith hydroxyethyl hydrazine in zone 20 have previously been disclosed inconjunction with each other, it is to be understood that eithertreatment could be performed in the absence of the other. Also,hydroxyethyl hydrazine or other hydrazine treating agent according tothe invention could be employed in zone 14 in place of hydrazine. Also,other hydrazine treating agents could be employed in zone 20 in place ofhydroxyethyl hydrazine, provided that the'volatility of the hydrazinetreating agent is not too great.

Petroleum fractions generally are suitable for stabilization ortreatment according to the invention. Thus, crude petroleum, reducedcrude, various distillates ranging from gasoline to lubricating oils andwaxes, etc. can be advantageously stabilized or treated according to thepresent invention. Other hydrocarbon materials, such as shale oil andfractions and conversion products thereof, are also advantageouslystabilized or treated according to the invention.

The following examples illustrate the invention:

Example I A Coastal petroleum crude was topped as indicated in thedrawing to obtain a 59 percent reduced crude. 1.5 volume percent of 50B. caustic soda was added to the, reduced crude in naphtha solution, andthe 1'6: suiting mixture was, held at 150 F. for 17 hours. In oneinstance, this treatment was carried out in the presence of 0.05 volumepercent hydrazine, and in a second instance hydrazine was not presentduring the treatment. In each instance,the product of the treatment wasstripped of naphtha and vacuum distilled to obtain a plurality ofdistillates, each constituting 10 percent of the charge to thedistillation and having endpoint as indicated in the table below. Eachdistillate was tested for color stability by measuring the N.P.A. colorthereof before and after subjection to a temperature of 221 F. for 16hours in an atmosphere of air.

The end points of the various cuts do not correspond closely for therespective distillations; the discrepancy is probably attributable todifferent degrees of removal of i aphtha from the respective materialsprior to the distilation. i

This example shows that the presence of hydrazine substantially improvesthe color stability of lubricating oil products obtained by treatment ofreduced crude with caustic soda at a temperature of 150 F. for 17 hours,followedby vacuum distillation to obtain lubricating oil distillates.

Example II Petroleum lubricating oil was stabilized by adding thereto aminor amount of a 54.4% aqueous solution of hydrazine. The lubricatingoil employed was a naphthenic oil which had not been solvent refined,and which had the following properties: Saybolt Universal viscosity atF., 547 seconds; Saybolt Universal viscosity at 210 F., 53.19 seconds;flash point 375 F.; fire point 430 F.; A.P.I. gravity 20.0. The oil hadan initial color of 21.4,

' Color, 0.1 Aqueous IIydrazine Concn, Wt. Percent Initial Aged Thisexample shows that aqueous hydrazine is capable of providing substantialimprovement of color and inhibition against color degradation oflubricating oil. Thus,

aqueous hydrazine can be added to a lubricating oil prior to storage ofthe latter, in order to prevent excessive discoloration during thesubsequent storage. Upon completion of the storage period, it isgenerally desirable to remove from the oil the water which wasintroduced with the original solution, and also any water formed duringthe storage period.

Example 111 Petroleum lubricating oil generally similar in properties tothat employed in Example II was stabilized against color degradation byincorporation of anhydrous hydrazine in the oil. The conditions oftesting were generally similar to those employed in Example II, and thefollowing table shows the results obtained:

Color, 0.1). Anhydrous Eydrazine Concn, Wt. Percent Initial Aged Thisexample shows that anhydrous hydrazine is also capable of providingsubstantial inhibition against color degradation in lubricating oil.After a storage period as discussed in Example II, it will generally bedesirable to remove from the lubricating oil any water which has beenformed during storage.

Comparison of Examples II and 111 indicates a synergistic action ofhydrazine and water. Thus, in Example H, 0.0272% of hydrazine and0.0228% of water gave an aged color of 22.1, whereas in Example III,only slightly less (0.025%) anhydrous hydrazine gave an aged color of27.5.

Example IV Petroleum lubricating oil generally similar in properties tothat employed in Example 11 was stabilized against color deteriorationby incorporating therein minor amounts of reaction products obtained byreacting ethylene oxide with hydrazine. The reaction products containedabout 80% of monohydroxyethyl hydrazine, and small amounts of otherreaction products of ethylene oxide with hydrazine. The procedure oftesting was generally similar to that employed in Example II, and thehydrazine derivatives provided inhibition against color degradationgenerally comparable to that obtained in Example II. If desired,hydroxyethyl hydrazine can be obtained in situ by adding ethylene oxideand hydrazine to the material to be treated under conditions promotingformation of hydroxyethyl hydrazine and reaction of the latter withconstituents of the treated material.

Example V Petroleum lubricating oil generally similar to that employedin Example II was stabilized against color deterioration byincorporating therein minor amounts of symmetrical dimethyl hydrazine.The procedure of testing was generally similar to that of Example II,and the dimethyl hydrazine provided inhibition against color degradation generally comparable to that obtained in Example II. Thelubricating oil, after the aging period, did not contain a water haze,and in this respect differed from the aged lubricating oils obtainedwith other hydrazine treating agents. Accordingly, in the case ofsymmetrical dimethyl hydrazine, and also other hydrazine derivatives nothaving a primary amino group, it is not necessary to remove water fromthe oil after the aging period.

The hydrazine treating agent employed according to the invention can beeither anhydrous or aqueous. The use of aqueous treating agentsgenerally provides better results with regard to color stabilizationthan the use of an anhydrous treating agent containing the same amountof hydrazine or derivative as the aqueous treating agent. Hydrazinehydrate is a particularly suitable form of aqueous hydrazine for useaccording to the invention.

The process of the invention is advantageous in that it permits the use,to improve petroleum products, of hydrazine treating agents which haveto low solubility in petroleum to be suitable as ordinary additives. Thesolubility is not a controlling feature since it is possible to react ahydrazine treating agent with petroleum constituents according to theprocess of the invention, even though the hydrazine treating agent isused in amounts larger than those which are soluble. Furthermore,elevated treating temperatures, where used, increase the solubility ofthe hydrazine treating agent in petroleum over the solubility atordinarytemperatures.

Saybolt color and A.S.T.M. gum rating of the gasoline after aging, ascompared with the same gasoline containing noadditive. On the Sayboltcolor scale, 30 is water white.

Saybolt color gum No additive 14 5. 2 10 p.p.m. of aqueous hydrazine 273 This table shows that aqueous hydrazine is effective,

though used in very small amounts, to provide improved color stabilityand gum rating of catalytic gasoline.

Aqueous hydrazine is also effective in reducing the color degradationoften caused by the use of conventional gum inhibitors and sweeteningadditives such as :1

phenylene diamine. The following table shows results obtained after 3weeks aging with catalytic gasoline similar to that discussed above:

No additive p p 32 ppm. of phenylene diamine 2 32'p.p.m. of phenylenediamine and 50 ppm. of

aqueous hydrazine 18 This table shows that aqueous hydrazine efiectively7' V, counteracts the color degrading tendency ofphenylene i,

diamine.

The invention contemplates the use of hydrazine or y derivatives asdefined herein in conjunction withother additives comprising aromaticcompounds having amino groups in the molecule, but not having thecharacteristic Saybolt color 14 nitrogen-to-nitrogen linkage ofhydrazine and derivatives, which other additives, when used in theabsence of hydrazine or derivative, 'ca'use 'color' degradation of thepetroleumfractiori to which th'ey'ar'e' added. 'Insu eh use, thehydrazine or derivative provides a beneficial counteracting of the colordegrading tendency of the other additive. Penylene diamine, N,Ndimethyl-pphenylene diamine, N,N'-di-secondary butyl-p-phenylenediamine, and N,N'-di-secondary hexyl-p phenyle'n'e dianiine, aniline,toluidine, Xylidine, ethyl anilines, cumidines, etc. are examples ofaromatic amino additives with which hydrazine or derivatives canadvantageously be used. i

In copending application Serial No. 726,058, filed April 3, 1958, as acontinuation-in-part of the present application, petroleum lubricatingoil compositions containing hydrazine and certain derivatives thereofare claimed.

The invention claimed is:

1. Process for improving the color stability of hydrocarbon materialwhich comprises contacting a normally liquid petroleum hydrocarbonfraction with a hydroxyalkyl hydrazine containing at least onehydrogen'atom attached to a nitrogen atom in the molecule, therebytoreact the hydroxyalkyl hydrazine with constituents of the hydrocarbonmaterial which normally cause poor color stability, and separating thereaction products from the treated fraction. i

2. Process according to claim 1 wherein the product of such contactingis distilled to obtain distillates having improved color stability.

3. Process according to claim 1 wherein the amount of said treatingagent is within the approximate range from 0.005 to 0.5 weight percentbased on said hydro carbon fraction.

4. Process for improving the color stability of hydrocarbon materialwhich comprises contacting a normally liquid petroleum fraction withadded alkali metal hydroxide and a treating agent selected from thegroup consisting of hydrazine, alkyl hydrazines and hydroxyalkylhydrazines, said treating agent containing at least one hydrogen atomattached to a nitrogen atom in the molecple, separating the treatedhydrocarbon material from excess alkali metal hydroxide, thereby toobtain a treated hydrocarbon material having superior, color stabilityto that of a treated hydrocarbon material obtained by the same procedurein the absence of said treat- 1 s a en 5. Process for improving thecolor stability of hydrocarbon material which comprises contacting anormally liquid petroleum hydrocarbon fraction with added Water and atreating agent selected from the group consisting of hydrazine, alkylhydrazines and hydroxyalkyl hydrazines, said treating agent containingat least one hydrogen atom attached to a nitrogen atom in the molecule,thereby to react the treating agent with constituents of the hydrocarbonmaterial which normally cause poor color stability, and to obtain atreated hydrocarbon" material having superior color stability to thatof. the original hydrocarbon material.

References Cited in the file of this patent UNITED STATES PATENTS1,906,044 Burk Apr. 25, 1 933 1,958,744 Cross May 15, 1934 2,027,394McMullan Jan. 14, 193 2, 2,67 Rather Dec- 1, 6 2,304,242 Cloud Dec 8,1942 2,328,190 Burk et al. Aug. 31, 1943 2,353,690 Clarkson et a1. July18, 1944 2,508,617 Mastin May 23, 1950 2,589,450 Stanton Mar. 18, 19522,712,556 Darling July 5, 1955 2,729,690 Oldenburg Jan. 3, 1956 FOREIGNPATENTS 423,938 Great Britain Feb. 11. 1935 OTHER REFERENCES TheChemistry of Hydrazines, John Wiley and Sons,

49 Inc. 1951, pages 226-227.

1. PROCESS FOR IMPROVING THE COLOR STABILITY OF HYDROCARBON MATERIALWHICH COMPRISES CONTACTING A NORMALLY LIQUID PETROLEUM HYDROCARBONFRACTION WITH A HYDROXYALKYL HYDRAZINE CONTAINING AT LEAST ONE HYDROGENATOM ATTACHED TO A NITROGEN ATOM IN THE MOLECULE, THEREBY TO REACT THEHYDROXYALKYL HYDRAZINE WITH CONSTITUENTS OF THE HYDROCARBON MATERIALWHICH NORMALLY CAUSE POOR COLOR STABILITY, AND SEPARATING THE REASONPRODUCTS FROM THE TREATED FRACTION.
 2. PROCESS ACCORDING TO CLAIM 1WHERE THE PRODUCT OF SUCH CONTACTING IS DISTILLED TO OBTAIN DISTILLATESHAVING IMPROVED COLOR STABILITY.
 3. PROCESS ACCORDING TO CLAIM 1 WHEREINTHE AMOUNT OF SAID TREATING AGENT IS WITHIN THE APPROXIMATE RANGE FROM0.005 TO 0.5 WEIGHT PERCENT BASED ON SAID HYDROCARBON FRACTION.